Pelvic diaphragm: muscular partition between the true pelvis and the perineum, forming the gutter-shaped pelvic floor.
Formation and Extent
Formed by levator ani and coccygeus muscles of both sides, with their covering fasciae.
Incomplete anteriorly: gap for the urethra in males, and the urethra and vagina in females.
Functions
Provides principal support to the pelvic viscera and has a sphincteric action on the rectum and vagina.
Assists in raising intra-abdominal pressure during defecation, micturition and parturition.
Openings
Two openings: hiatus urogenitalis and hiatus rectalis.
Hiatus urogenitalis: triangular gap between the anterior fibres of the two levator ani muscles; transmits the urethra in males, and the urethra and vagina in females.
Closed from below by the urogenital diaphragm.
Hiatus rectalis: round opening between the perineal body and the anococcygeal raphe, giving passage to the anorectal junction.